Washington (AFP)

At the end of January, shortly after the confirmation of the first official case in the United States of what was not yet called Covid-19, the New York Stock Exchange was at an all-time high and Donald Trump's main concern was the impact of Boeing's woes on the economy.

"The American dream is back, stronger than ever", declared the American president in Davos, evoking a "prosperity (...) without precedent".

Nine months later, 60 million Americans were infected, according to one model, and more than 300,000 died, directly or indirectly, from the pandemic, making the virus the third leading cause of death in 2020.

Millions of Americans have lost their jobs, and despite an impressive rebound in the third quarter, many have not found jobs since.

What collapses the most reliable electoral argument of American presidents in search of a second term, that of economic strength.

The defeat of Mr. Trump at the polls Tuesday is far from assured, and he himself wants to believe that his Democratic opponent, Joe Biden, for lack of having carried out a real campaign on the ground, will be sanctioned by the voters.

But his management of the crisis certainly cost him votes, just as the war in Iraq had done for George W. Bush and the Republicans in the legislative elections of 2006.

That of Kimberly McLemore, 56-year-old jeweler, is already lost.

For the first time in her life, this St. Augustine, Florida voter voted Democrat.

Specifically because of the pandemic.

"In conscience, I cannot vote for this man," she told AFP.

"He spread disinformation, if not outright lied."

The icing on the cake: his two parents, 86 and 89, also Republicans, also voted Biden.

But how many Kimberly will there be in the country?

- Some voices -

"Covid, Covid, Covid! The media + Fake News + have only that word to mouth", recently lamented Donald Trump in a meeting.

From the start of his campaign, the virus frustrated the tribune: his first post-containment meeting, in a room in Tulsa in June, undoubtedly created a source of contamination.

The White House was another cluster, and the head of state himself fell ill a month before the election.

For months, polls have shown that Americans have severely rated the leader for his handling of the health crisis: only 40% approve, according to a recent Gallup poll, against 60% in March.

The shift is noticeable in one of the traditional targets of Republicans: seniors.

In Florida, for example, where the virus has killed 13,000 people over the age of 65, Joe Biden is ahead of Donald Trump in this age group, at 55% against 40%, according to the Quinnipiac Institute, which totally reverses the report. force of 2016.

But the popularity ratings are too general to distinguish a "Covid effect" on the election.

Researchers have therefore performed a detailed analysis to isolate this effect, published Friday in the journal Science Advances.

Using a panel of 300,000 people in 2019 and 2020, and local data on virus mortality, they were able to link Donald Trump's decline in popularity to the death toll from the coronavirus locally, by county. .

A doubling of the number of deaths in the previous 30 days, in a given county, is linked to a drop of 0.14 percentage point in voting intentions for Donald Trump, and 0.28 points for Republican Senate candidates, according to their calculations.

"A lot of elections are played at very thin margins," points out the study's lead author Christopher Warshaw of George Washington University.

"It is very possible, according to our results, that the Covid will cause the president and his party to lose a half point or a point in certain states or counties."

That might be enough for Mr. Biden.

In 2000, the presidential election was played out by a few hundred votes in Florida.

And four years ago, a meager lead of 77,000 votes in three states (Pennsylvania, Michigan, Wisconsin) tipped the election in favor of Mr. Trump.

© 2020 AFP